In food shops in convenience stores, department stores, super markets, etc., foods, such as daily dishes, deep-fried dishes, noodles, and salads are placed in food containers, e.g. tray, cup or bowl, and sold. Heat resistance is required of these food containers to a temperature capable of being resistant to microwave oven heating for less oil content foods (90° C.), to a temperature capable of being resistant to microwave oven heating for abundant oil content foods (150° C.), or to a temperature capable of browning the top of gratin or Dria (180-250° C.). As the food containers having a heat resistance up to 90-150° C., containers having a four layer structure of A, B, C, D from the inside, wherein the heat resistance is imparted by using a PP layer containing 20-60% by weight of inorganic filler as the outermost D layer are proposed (see Patent Document 1), and techniques for fabricating a resin composition composed of 40-80% by weight of a mixture of 10% by weight or more of PP resin and PE resin and 20-60% by weight of talc are also proposed (see Patent Document 2). However, since the main body of the containers formed by these techniques is PP resin having a melting point of around 160° C., they cannot be used as a container having a heat resistance up to 250° C. for handling gratin etc.
As the container having a heat resistance up to 180-250° C., in general, molded containers using C-PET resin (crystallization accelerator is added.) are applied.
Moreover, a container for oven capable of handling −40° C.-250° C. is proposed formed of a mixture of 100 parts by weight of all aromatic polyester composed of a repeating unit of:
and forming an optically anisotropic fused phase, filled with 25-500 parts by weight of an inorganic compound (see Patent Document 3).
In addition, a method of manufacturing a sheet for food containers is proposed utilizing undried recovered PET flakes (see patent Document 4), but this sheet for food containers is not heat-resistant.